Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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926
FXUS63 KDTX 190508
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
108 AM EDT Mon Aug 19 2019


.AVIATION...

Light flow and plenty of available near surface moisture will allow
for areas of fog and low clouds to develop overnight. The onset will
be delayed until the middle/high clouds from the exiting convection
translate east of the region. Clouds should lift and scatter across
the north rather quickly as a cold front settles south through the
area during the morning. Across the Detroit terminals, the clouds
should slowly lift - but may have a hard time completely mixing out.

For DTW...Light fog and low cloud development is expected early in
the forecast period. Lingering ceilings below 5kft are likely
Monday.

.DTW THRESHOLD PROBABILITIES...

* Moderate for ceilings aob 5kft tonight and Monday.

&&

.PREV DISCUSSION...
Issued at 319 PM EDT Sun Aug 18 2019

DISCUSSION...

The numerous showers and thunderstorms which worked through
southeast Michigan this afternoon (a few severe), helped drop
temperatures into the 70s, leading to a significant stabilization of
the airmass (see 19z SPC mesoscale analysis). Thus, confidence is
low that activity with the actual cold front will be severe, not to
mention the coverage of activity is in question this far north. At
least, the 17z Rap looks to be trending in the right direction (less
activity). None-the-less, still a short window to destabilize (lower
80s) before sunset, and the upper level dynamics/shear (50 knots of
effective shear) needs to be respected as it sweeps through around
00z. On the flip side, could be in the shadow of the organizing
thunderstorm complex developing over central Indiana into Ohio where
the max instability (MLcapes of 2500 J/kg) presently resides, which
should help mitigate our severe chances as well.

Strong upper level low (545 DAM at 500 MB) over northern Manitoba
will be the main influence/director to our weather over the several
day, as it swings through Ontario during the mid week period,
supporting a significant cool down.

An extension of trough axis will be lifting through the northern
Great Lakes tonight, with 500 MB heights beginning to rebound over
southern Lower Michigan on Monday. Thus, the cold front that slips
through southeast Michigan tonight, will more or less wash out. With
the lingering low level moisture, especially with the rainfall from
this afternoon, and weak surface convergence, some fog and/or low
stratus development appears possible late tonight.

500 MB heights rise to around 588 DAM on Monday, but still enough
residual low level moisture/850 MB Theta-e and instability around to
support low chance pops along/south of I-94.

Pseudo zonal upper level flow with upper level energy/PV coming out
of the Rockies and tracking through Midwest Monday night. It appears
the potential thunderstorm complex will track off to the southeast
during Tuesday and miss the state. This will also help cut off some
of the moisture advection ahead of the cold front, which tracks
through late Tuesday night or Wednesday. Thus, a dry frontal passage
remains possible.

Warmer temperatures, with highs in the 80s, will remain in place on
Wednesday before cooler temps come back for the remainder of the
week.  By Thursday, 850mb temps will be back in the single digits. A
slight chance of precipitation also remains in the forecast
Wednesday afternoon, as a wave passes over.  The rest of the
forecast period going into the weekend will feature pleasant
temperatures and dry weather as high pressure settles in over the
region.

MARINE...

A low pressure system lifting through lake Superior this afternoon
will pull a cold front through the region this evening. This front
may produce another round of thunderstorms this evening before
pushing east of the area. Southwesterly winds will veer westerly
behind this front tonight and to the northwest on Monday as a
secondary front drops through the region. Winds will be strongest
this evening out of the southwest with gusts reaching 25 knots.
Though cooler air will advect in behind the front tonight, high
pressure building in will weaken the gradient and prevent stronger
gusts tonight and Monday. Though mostly a dry forecast beyond
tonight, additional showers and thunderstorms will continue to be
possible over Lake Erie and St. Clair with the frontal boundary
stalling nearby.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

AVIATION.....MANN
DISCUSSION...SF/SP
MARINE.......DRK


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at www.weather.gov/detroit.



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